An increasing concern for environmental problems these days leads to a higher demand for fuel efficient vehicles. Rubber compositions for automobile tires are also desired to have excellent fuel economy. There are, for example, conventional rubber compositions for automobile tires that contain a conjugated diene polymer such as polybutadiene or styrene-butadiene copolymers, a filler such as carbon black or silica, and oil or the like for ensuring flexibility.
Patent Literature 1 for example proposes a method for improving fuel economy. The method uses a diene rubber (modified rubber) modified with an organic silicon compound containing an amino group and an alkoxy group. While the use of the modified rubber enhances the reaction efficiency between silica and rubber (polymer) to improve fuel economy, it tends to increase Mooney viscosity so that processability can be deteriorated. It is thus difficult to improve both fuel economy and processability. Moreover, the modified rubber and silica are bound too densely so that rubber strength or abrasion resistance may be reduced.
Furthermore, since rubber compositions for automobile tires need to be excellent in wet-grip performance and handling stability for safety reasons, improved methods are needed which can achieve a good balance of high levels of these properties and fuel economy, processability, rubber strength, and abrasion resistance.